Chapter 2: The Sun and other stars

﻿Chapter 2 Introduction﻿

Have you ever looked up at night and seen the Milky Way Galaxy? It's hard to miss because it's the only thing you can see. All of the stars and planets visible to your eyes -including Earth- are part of it. Beyond the Milky Way Galaxy are hundreds of billions of other galaxies.

SummaryThe sun is a huge mass of hot gases that produces huge amounts of energy. It is the source of most of the energy on Earth. The sun has several layers: the core, the radiation zone, the convection zone, the photosphere, and the corona. Some of the visible features of the sun are solar prominences, solar flares, granules, and sunspots.Click on the button below to watch and interact with a video.

Scientists classify stars by absolute magnitude, surface temperature, size, and color. Most stars are in the main sequence. Stars undergo a series of changes from nebula to protostar to main-sequence star to expanding star to red giant to planetary nebula and white dwarf. Scientists learn about stars by using telescopes and other instruments to study the energy that stars release into space.Click on the button below to watch and interact with a video.

A galaxy is a group of stars, gas and dust. Many galaxies rotate around a central core. The sun is in the Milky Way Galaxy. The Milky Way Galaxy is part of a galactic cluster called the Local Group. Also visible in the night sky are nebulae, which are clouds of gas and dust in which stars form.